Regulatory Matters (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 capital, Minimum	0.045
Common equity tier 1 capital, Well Capitalized	0.065
Common equity tier 1 capital	0.1231	0.1297
Tier 1 capital, Minimum	0.060
Tier 1 capital, Well Capitalized	0.080
Tier 1 capital	0.1312	0.1321
Total capital, Minimum	0.080
Total capital, Well Capitalized	0.100
Total capital	0.1527	0.1501
Leverage ratio, Minimum	0.040
Leverage ratio, Well Capitalized	0.050
Leverage ratio	0.0938	0.1034
Common equity tier 1 capital	$ 1,459,152	$ 1,275,148
Tier 1 capital	1,555,574	1,299,398
Total capital	1,810,503	1,476,302
Risk-weighted assets	11,857,146	9,834,051
Average total assets for the leverage ratio	$ 16,583,232	$ 12,568,563
United Community Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity tier 1 capital	0.1320	0.1487
Tier 1 capital	0.1320	0.1487
Total capital	0.1421	0.1554
Leverage ratio	0.0942	0.1163
Common equity tier 1 capital	$ 1,559,356	$ 1,458,720
Tier 1 capital	1,559,356	1,458,720
Total capital	1,678,689	1,524,267
Risk-weighted assets	11,815,993	9,810,477
Average total assets for the leverage ratio	$ 16,554,227	$ 12,545,254